Continuously operable mixing and kneading device

ABSTRACT

A continuously operating mixing and kneading apparatus for uniformly blending powdered plastics and cut pieces of calendered plastic sheet material comprising a first vertical casing with axial worm rotating on a shaft, a conical feed hopper projecting from the open end of the vertical casing and the shaft-carrying bar means at the top of the hopper and radially inclined blades between the bars and the worm, and additional feeding means constituting a horizontal casing, a second worm and a second feed hopper, the second worm rotating radially in respect to the first worm to uniformly and smoothly convey the proportions of materials delivered to it by the second worm while the rotational movement of the bars and the blades provides smooth and uniform feeding.

United States Patent 72] Inventor Fritz Sutter Pratteln, Switzerland 2'11 Appl. No. 724,735 [22 Filed Apr. 29, 1968 {45] Patented Jan. 5, 1971 [73] Assignec Buss Aktiengesellschalt Basel Switzerland a corporation of Switzerland [32] Priority Apr. 27, 1967 l 3 3 Switzerland [31 No. 6157/67 Pat. 448-481 [54] CONTINUOUSLY OPERABLE MIXING AND Primary Examiner-Robert W. Jenkins AtlorneyAbraham A. Saffitz ABSTRACT: A continuously operating mixing and kneading apparatus for uniformly blending powdered plastics and cut pieces of calendered plastic sheet material comprising a first vertical casing with axial worm rotating on a shaft, a conical feed hopper projecting from the open end of the vertical casing and the shaft-carrying bar means at the top of the hopper and radially inclined blades between the bars and the worm, and additional feeding means constituting a horizontal casing, 21 second worm and a second feed hopper, the second worm rotating radially in respect to the first worm to uniformly and smoothly convey the proportions of materials delivered to it by the second worm while the rotational movement of the bars and the blades provides smooth and uniform feeding.

F1 1 -il- PATENTEU JAN 5157! I I I I I I u I [NV ENTOR FRlTZ SUTT ER ATTORNEY This invention concerns a continuously operable mixing and kneading device which has a shaft rotating and oscillating simultaneously in a casing and having a feed hopper at one end wherein rotating blades and a feed worm are provided.

Among the materials which are to be mixed, kneaded and chemically combined are those having different characteristics, e.g. solids with solids, solids with liquids and/or gases. Devices for continuous mixing and kneading known at present have great disadvantages, if the rnaterial to be fed is composed of components having a very different physical nature, such as for example in respect to size of particles, specificgravity and shape, these show correspondingly different fiow behavior and consequently have a high tendency to separatewhich causes unsteady and nonuniform conveyance in this known method.

The object of the invention is to eliminate these disadvantages. The mixing and kneading .device proposed in .ac-

cordance with the invention is characterized in that an additional feed device is attached to the feed hopper in the lower region thereof which'has a worm running radially to the feed worm and whose casing is provided with a second feed hopper. f p

The continuously operable mixing-and kneading device'of the present invention may be advantageouslyemployed, particularly in the production of sheets of plastics on a calender In this case, the kneader provides continuously homogenous heating. mixing and kneading of the material, which then according to requirement is only lightly sintered or plasticized, passed through nozzles into a suitable'form, and is then continuously fed to the calender. On subsequent 'calendering a band of different width develops which is 'cut to size on both sides. With this arrangement, two relatively narrow strips of waste result which must be passed again through the process of production as rationally as possible. These strips are as is known, cut into small pieces which are refed with the powdered plastics into the feed hopper of the kneading device. It has been proved .in practice with. conventional mixing and kneading devices that, due to the higherspecific gravity of the pieces separationcan take pla ce so that after a short'time, pieces or powder only are fed to the kneading device. These disadvantages do not arise in the proposed mixing'and kneadingdevice. 7

An embodiment of the subject matter of the invention is shown, by way of example only, partly in section in the accompanying drawing.

The mixing and kneading deviceshown hasa cylindrical casing 1 wherein a shaft 1' having a worm is adapted to rotate and oscillate simultaneously. The casing 1 is secured on a support 2 and there is provided a feedIhopper which consists of a longitudinally divided upper part4 and a lower part 4. The lower part 4' is provided with a cylindrical portion 4" which is connected to the feed aperture of thecasing l. A vertical shaft 5 is disposed in the upper hopper 4, 4. '4", which is carried in bearings (not shown) and driven by a separate drive.

The said vertical shaft 5 carried at the top simple horizontal bars 6 of rectangular shape. Radially inclined blades 7 are disposed therebelow whilst theshaft isalso provided with a worm thread 8 in the region of the cylindrical portion 4 of the hopper.

A horizontal projection I0 is disposed on the part 4 of the hopper, which carries a feed casing I l'.The two parts 10 and II form an additional feed device, which also has a feed worm I7 running horizontally. An electric motor 21 drives the worm l7 and is connected to the shaft of the latter via a gear 15. The

To dismantleand clean the device, screws 12 between the flange of the horizontal projection 10' and the feed casing II are released so that the group consisting of the parts ll, l3, l5, l7 and 21 may be pushed to the'right on the T-shaped slide 5 trackl8uptoastop20. a

For cleaning and checking thecasing and the worm I the whole unit is raised by means of the hydraulic lifting device 9 so that the hopper 4, 4, 4" together with the shaft 5 is accessible.

In operation the waste strips are} cut continuously in a cutting machine and the small pieces are conveyed into the hopper 13 by a suitable device, for example a pneumatic conveyor. The operator watches the level ofv the bits constantly in the inspection glass and adjusts the speed of the worm shaft 17 accordingly. If the level is too high, then[adjust an adjustment to a higher speed is made by means of the hand wheel 16. or vice versa. As, when operating with a calender; the-waste strips do not have any great difference in width, the adjustment will not cause much work. It is however possible to make the adjustment automatic in that a sensor of the level is built into the hopper 13 which controls the adjustment of the hand wheel 16 and thereby the speed or the worm shaft 17. A coupling of the adjustment of the speed with the drive to the shaft 5 and of the subsequent kneader'is also possible. Finally it may be required that the weight of the bits should be kept in exact proportion to the powder fed through the hopper 4. In this case each feed hopper could be' fille'd via a weighing scale.

The utilization of the salvaged bitsis only one of many possible uses of the proposed mixing and kneading device, as it is conceivable that one or moreadditional materials could have to be added to the material inv the hopper 4, which for some reason or other have to bebrought together in as short a time as possible before the manufacturing process. For this purpose several additional feed arrangements can be built onto part 4 of the hopper without any difficulty; the dosing may take place manually in that 'weighed portions are delivered chargewise to the hoppers or alternatively it can be made automatic. In this case eaChhopper has its individual 40 dosing device and level sensor andgasuitable safety'device would slow down or stop all dosing devices if one of the drives a first conical feed hopper projecting from'an open end of said first casing through which said shaft extends'along a longitudinal axis thereof;

said shaft carrying bar members 'at-the top of said feed hopper and further carryingradijally inclined blades at below said bars to assist in feeding the materials to be mixed to said worm which rotates; and

an additional feeding-means communicating at right angles with the base portion of said firsticonical feed hopper which brings a second stream of material into the upper part of said worm, saidadditional means including a horizontal casing, a second wonn; a collar connecting said horizontal casing to said vertical casing with an opening in said collar providingcomm'unication between said vertical casing'and said horizontal casing, and a second feed hopper, said second worm rotating radially in respect to said first worm of said first casing, whereby the movement of said first worm, uniformly and smoothly conveys the proportions ofmaterials delivered to it by said second worm while the rotational movement of said bars and said inclined blades-on said first shaft assist smooth and uniform feeding, 2. An apparatus as claimed in claim I, wherein said second feed hopper is provided with an'inspection glass.

3. An apparatus as claimed in claiml-,.wherein said second feed hopper is provided with sensing means to sense the level 75 of material in said second hopper. 

1. A continuously operating mixing and kneading apparatus adapted for uniformly blending powdered plastics and cut pieces of plastic to continuously feed a calender, comprising: a first cylindrical vertical casing having a worm disposed axially thereof on a shaft; a first conical feed hopper projecting from an open end of said first casing through which said shaft extends along a longitudinal axis thereof; said shaft carrying bar members at the top of said feed hopper and further carrying radially inclined blades at below said bars to assist in feeding the materials to be mixed to said worm which rotates; and an additional feeding means communicating at right angles with the base portion of said first conical feed hopper which brings a second stream of material into the upper part of said worm, said additional means including a horizontal casing, a second worm, a collar connecting said horizontal casing to said vertical casing with an opening in said collar providing communication between said vertical casing and said horizontal casing, and a second feed hopper, said second worm rotating radially in respect to said first worm of said first casing, whereby the movement of said first worm uniformly and smoothly conveys the proportions of materials delivered to it by said second worm while the rotational movement of said bars and said inclined blades on said first shaft assist smooth and uniform feeding.
 2. An apparatus as claimed in claim 1, wherein said second feed hopper is provided with an inspection glass.
 3. An apparatus as claimed in claim 1, wherein said second feed hopper is provided with sensing means to sense the level of material in said second hopper. 